Instead of banishing/fearing the doomguards, have your pitlord attack them. Fear/Banish is just another variable that I had to keep an eye on so I used my pit, attacked them right away and he held aggro the entire fight. Also nuke him as soon as he becomes hostile. Some say wait for pit to start DPS, I say otherwise. Nuke nuke nuke!

Also after his apocalypse, feel free to use your Pit Lord's charge willingly.

Just keep on going! You'll get better and better. Make sure you've got food/flask + any other buff you can think of.

Try banishing or fearing the Doomguards. Alternatively you can make your Pit Lord attack it at least once ,and then soulshatter so that your Pit Lord has higher aggro than you do to the Doomguard. That way the Doomguard will attack the Pit Lord instead of you.

If you do the second just make sure you do banish or fear the Doomguards when you go to re-enslave the Pit Lord.

If you bring a potion of purification you can dispel the Curse of Doom at least once in the fight, that makes him recast it and reset the timer. Doing so gives you 15ish minutes to kill him. After the 2 rotations of Imps > Felhunters > Doomguard he will ONLY summon Imps. If you can get the imps under control you can use them for infinite embers if you are destro, and spam the shit out of Shadowburn to eat the last 20% of his health in a matter of seconds.

Make sure you are using the Pit Lord's stun for maximum damage, while stunned by it the boss takes 100% bonus damage, so time your shit to do the most damage possible. Example of this would be to Conflag twice so your next two Chaos Bolts are fast, and then charge up the first Chaos Bolt and make your pet stun him right before it hits, so you can fully charge and throw the second one before the stun ends.

After my 32nd try, I figured out I suck... I honestly just.. I either die or mess up, It doesn't need a nerd at all, I just need to get sharper and better -_-

It definitely takes time. Can't tell ya how many times I failed, then one run it "clicked" and I did everything flawlessly. Also yeah, if you don't have a potion of purification, get some! You can only use it once though, so wait til his curse of doom has a few seconds left then pop it.

Also, as a trick, if you want more time, as soon as you enslave the pit lord, RUN to the anvil, down the steps. Park your pit lord there. Kill imps/doomguards down there. No need to dodge/interrupt/curse of doom anything. You'll eventually have to go up and kill him, but without the demon spawns (just imps)

Felhunters will stay above so you'll have to go up and kill them. Tell your Pit lord to "stay" and go up there and solo em down without the worry of having them eat your enslave. Just watch out for the apocalypse since you can't interrupt it.

The main point I hear about that causes people to trip up is the felhunters devouring your enslave on the pit lord. Take a deep breath before each attempt and go over the following.

Do you have healthstones?
Do you have your imp sacrificed?
Is the glyph of enslave active?
Things that make this fight easier to manage include setting a way for you to see if Kanrethad is currently targeting you with whatever he may be casting (setting his as focus does a pretty good job of this), a way to track your remaining duration on enslave (if you find that your pit lord is frequently breaking and thus causing major issues), and a way to use the move to command for you pit lord (I use a razer naga with pet bar mapped to a ctrl mod key).

The best time to re-enslave the pit lord is when Kanrethad makes his way over to summon the pack of felhunters, quickly dismiss the pitlord, stun him with shadowfury, and re-enslave him. This has to be done quickly, because as soon as those felhunters start coming, you need to have your pit lord out of their conic line of sight (you can see a very good spot to set him in the video I linked) Use RoF to get snap aggro on the felhunters, and (this part is tense) once all 3 are on you, have your pit lord use his cleave on them. You should be able to finish them off quickly enough that you can stop cataclysm with charge.

The 3rd summon is a doomguard, and there are 2 methods of dealing with it. The method in the video is to let the pit lord just have aggro, and this method works fine, and in my opinion is the easier one. The 2nd is to use banish on it, but that just adds another variable that you have to track, every 30 seconds.

Your gear should allow you to drop Kanrethad before the 2nd doomguard, so you shouldn't need to worry about having 2 out.

The last major part of the fight is dispels. This is the reason you sacrifice the imp, because of the self dispel you get from him. The 2 ways of clearing the curses that Kanrethad will place on you are through self dispelling with cleanse magic (imp dispel) and through the pit lord's breath. Standing in his breath attack will clear you of all of Kanrethad's curses, other than the psuedo enrage that one shots you after 7 minutes.

TL;DR

Make sure you have everything set up before you start the fight (buffs, spells, glyphs, macros ,etc)
Watch out for Chaos Bolts aimed at you, and break los with them via lock portal.
Always keep yourself clean of debuffs with dispels.
Remember that you need to re-enslave at some point.
Don't panic, and take a break if you get frustrated.

It definitely takes time. Can't tell ya how many times I failed, then one run it "clicked" and I did everything flawlessly. Also yeah, if you don't have a potion of purification, get some! You can only use it once though, so wait til his curse of doom has a few seconds left then pop it.

Also, as a trick, if you want more time, as soon as you enslave the pit lord, RUN to the anvil, down the steps. Park your pit lord there. Kill imps/doomguards down there. No need to dodge/interrupt/curse of doom anything. You'll eventually have to go up and kill him, but without the demon spawns (just imps)

Felhunters will stay above so you'll have to go up and kill them. Tell your Pit lord to "stay" and go up there and solo em down without the worry of having them eat your enslave. Just watch out for the apocalypse since you can't interrupt it.

Also, what spec are you?

I am destro spec! I heard it was best? I got REALLY sloppy before I came off, I can get it to around 30% then f up somehow -_- But yea I guess its just try and try and perfect it

Sounds like the doomguards are what's getting you, if you're getting to infinite imps. Best strategy (like most said) is letting the Pit take the aggro. Also, your best chance to reset your enslave is when Kan starts summoning a doomguard, which is easy on the first doomguard but not so much on the second. for the second doomguard I would dismiss and re-enslave, (which causes aggro to reset on the 1st doomguard), send the pit back on the 1st doomguard and smack it a few times. by that point the second one should be out, have the pit smack that one and fel flame breath on it, then soul shatter and use gate to clear aggro. It worked to hold the doomguard aggro for me until I killed him.

Good luck! I wiped countless times, it just takes that little bit of luck and hard work to get a flawless run.

The best advice I can give is don't get frustrated and try new things when you see a problem with your strat. I think of myself as a pretty good player and it still took me more attempts than I could keep up with. I really like this questline though. It's good to have something non-mandatory that's so hard. I took about 12936 screenshots when I got the kill. My only complaint would be the duration on the curse he puts on you. You would have to be in pretty high end gear to kill him before it expires and a purification potion shouldn't be mandatory for the fight like it is.

I was trying the strat of using my gateway to LOS the Chaos Bolts. Being demonology I would run into problems with the doom lords. The pit lord just couldn't hold aggro and they would kill me. So I changed to the strat where you use your gateway constantly to keep up the debuff as much as possible. That way aggro is never an issue and I think he cast Chaos Bolt 1 time over the entire fight which I negated with our ward and Pact. To do this I found it easiest to put the gateways as close together as possible in the middle and setup Weak Auras to show duration on debuff and flash at me when it expired. I did run into an issue with the pit lord's health getting dangerously low while the 2nd doom lord was out so I used 1 full channel of Health Funnel followed up with Soul Shatter.

Random thoughts:

Take gateway as often as possible. Keeping that debuff up is the key.

This fight takes a lot of repeated attempts to get the rhythm down. You need to know what he is going to do at all times without having to think about it.

Send the pit lord behind a pillar right after interrupting Cataclysm before the fel hunter phase. If you want until he runs to summon them it may be too late. Depending on your spec, develop a quick way of killing the fel hunters. If they stay up too long you will run into issues interrupting the next Cataclysm. As demonology I would save fury for this and hit them with everything I had.

Sacrifice your imp and use Singe Magic as often as possible (while you have Seed of whatever or Agony) The Seed debuff he puts on you can have some nasty effects and caused real problems for me when I didn't dispel it. Also use Fel Flame Breath anytime you have these debuffs and Singe Magic is on CD.

Dismiss and re-enslave the pit lord while dude is summoning the doom lords.

Bring some purification potions, but don't use them until needed. DBM should call out when Doom is about to tick off.

Kanrethad doesn't cast the first Cataclysm so use the interrupt on something else like the Seed spell.

Also, dunno what UI you are using, but set a focus on him. Helps keep track of his casting bar when stuff starts getting complicated.

My tip is, if you're still wiping, to focus on each phase of the fight. Make sure you can flawlessly do imps. Then felhunters, then the doomguard. Take note of things you could do better on each phase. Then combine everything you've learned and you've got the fight.

I spent a lot of time getting each phase 100%, even if it cost me DPS on the boss. Learn, master the mechanics. Imps, felhunters, doom. Imps, felhunters, doom.

Best bet is to throw down 2-3 RoF while he summoning, then dance around in the imps while using breath. Use the macro that has him use the breath on you. I think the actual cone is a lot narrower than the graphic so you really have to dance around in the imps to get it to hit all of them. Don't forget to use Shadowfury here too.

So ive never been thr "O MY GAWN GREEN FYRE" type so i recently decided to go out a buy the book off the ah and finally give it a go. When the RP is over and you get the bit of time to dps him before he summons the pit lord, i have him at 87% or so by the time he comes out and i enslave it. I go through my portal to reset threat and it doesnt work lol. Kanrathed stays on me and never attacks the pit lord. I shatter and he attacks it for a bit and when i hit him again he sticks back to me.

Guess i need to try it again and not touch him until after i get th epit lord enslaved to see if it helps with aggro.

I tend to be at 170k+ by the time the pit lord comes out. Could be my issue.

He will still cast the DOTs on you. No way around that really. If you take the gateway every time the CD is up you can avoid the Chaos Bolts though. I don't think the gateway actually affects your aggro at all. Rather it just makes NPCs prefer attacking something else while you have the debuff. I could be wrong though. I don't run a threat meter.

He will still cast the DOTs on you. No way around that really. If you take the gateway every time the CD is up you can avoid the Chaos Bolts though. I don't think the gateway actually affects your aggro at all. Rather it just makes NPCs prefer attacking something else while you have the debuff. I could be wrong though. I don't run a threat meter.

Using the gateway will drop all of your threat as long as there are other targets who attack. If you are the only target, it does nothing.
However, in the Green Fire case, he will continue to target you and do his cast cycle as intended. In fact, he is unaffected by threat. This is of course logical because otherwise it would trivialize the encounter too much.